Characteristics of pore size distribution in municipal waste contaminated clay based on soil-water characteristic curve

To evaluate the soil-water character and microstructure of soils during contaminants migration, the soil-water characteristic curve (SWCC) of municipal waste contaminated clay at various depths are plotted. Subsequently, the pore size distribution was quantified using the small incremental method, and the microscopic image analysis of contaminated soil using scanning electron microscopy was verified. The results show that the municipal waste contaminated clay has a greater dry density and higher water content than the uncontaminated clay. With increases in depth, the contaminated clay has increasingly reduced dry densities, saturated volumetric water content and saturated permeability coefficient. The SWCC of the contaminated clay is for Van Genuchten model and divide into three zones, converging with each other, becoming steeper and closer to that of the uncontaminated clay with increased depth. The pore size distribution of the contaminated clay determined by the small incremental method based on the SWCC is consistent with that of by MATLAB based on scanning electron microscopy (SEM) images. With reduced depth, the pore size distribution develops from minor-pores and micro-pores but no macro-pores. The migration of contaminants in clay reduces the porosity and pore size of the clay, as well as increases the matric suction.